﻿using System;
using System.Collections.Generic;
using System.Text;
using System.Web;
using System.Text.RegularExpressions;
using System.IO;
using System.Drawing;

namespace Net4.Common.Entities
{
    public class AttachmentManager
    {
        private static AttachmentManager _Instance = new AttachmentManager();

        public static AttachmentManager Instance
        {
            get { return _Instance; }
        }

        private AttachmentManager() { }

        public string SaveAttachment(HttpPostedFile postedFile, string fileName)
        {
            if (!IsAcceptFile(fileName))
            {
                throw new Exception("文件类型错误.");
            }
            string filepath = GetPhysicalStorageLocation(fileName);
            if (File.Exists(filepath))
            {
                throw new FieldAccessException("文件已存在.");
            }
            postedFile.SaveAs(filepath);
            if (IsImage(fileName)) //生成缩略图
            {
                MakeThumbnail(filepath, GetPhysicalStorageLocation(ImageInfo.SNAPSHOTSTRING + fileName),
                    170, 130, "Cut");
            }

            filepath = RelativeStorageLocation + fileName;
            return filepath;
        }

        public void DeleteAttachment(string fileName)
        {
            string filepath = GetPhysicalStorageLocation(fileName);
            try
            {
                if (File.Exists(filepath))
                {
                    File.Delete(filepath);

                    if (IsImage(fileName)) //删除缩略图
                    {
                        filepath = GetPhysicalStorageLocation(ImageInfo.SNAPSHOTSTRING + fileName);
                        if (File.Exists(filepath))
                        {
                            File.Delete(filepath);
                        }
                    }
                }
            }
            catch (Exception e)
            { }
        }

        /// <summary>
        /// Gets the physical storage location.
        /// </summary>
        /// <param name="fileName">Name of the file.</param>
        /// <returns></returns>
        public string GetPhysicalStorageLocation(string fileName)
        {
            return PhysicalStorageLocation + fileName;
        }

        /// <summary>
        /// Get the physical location for saving the file.
        /// </summary>
        public string PhysicalStorageLocation
        {
            get
            {
                return WebUtil.CurrentHttpContext.Server.MapPath(WebUtil.UploadDirectory);
            }
        }

        public string GetRelativeStorageLocation(string fileName)
        {
            return RelativeStorageLocation + fileName;
        }

        public string RelativeStorageLocation
        {
            get
            {
                return VirtualPathUtility.ToAbsolute(WebUtil.UploadDirectory);
            }
        }

        public bool IsAcceptFile(string extension)
        {
            string expression = ".jpg|.gif|.png|.bmp|.rar|.zip|.doc|.docs|.ppt|.txt|.pdf|.xml|.swf|.wmv|.xls|.mp3|.rft|.exe";
            Regex regex = new Regex(expression, RegexOptions.IgnoreCase);
            return regex.IsMatch(extension);
        }

        public bool IsImage(string extension)
        {
            string expression = ".jpg|.gif|.png|.bmp";
            Regex regex = new Regex(expression, RegexOptions.IgnoreCase);
            return regex.IsMatch(extension);
        }

        /**/
        /// <summary>
        /// 生成缩略图
        /// </summary>
        /// <param name="originalImagePath">源图路径（物理路径）</param>
        /// <param name="thumbnailPath">缩略图路径（物理路径）</param>
        /// <param name="width">缩略图宽度</param>
        /// <param name="height">缩略图高度</param>
        /// <param name="mode">生成缩略图的方式</param>    
        private void MakeThumbnail(string originalImagePath, string thumbnailPath, int width, int height, string mode)
        {
            Image originalImage = Image.FromFile(originalImagePath);

            int towidth = width;
            int toheight = height;

            int x = 0;
            int y = 0;
            int ow = originalImage.Width;
            int oh = originalImage.Height;

            switch (mode)
            {
                case "HW"://指定高宽缩放（可能变形）                
                    break;
                case "W"://指定宽，高按比例                    
                    toheight = originalImage.Height * width / originalImage.Width;
                    break;
                case "H"://指定高，宽按比例
                    towidth = originalImage.Width * height / originalImage.Height;
                    break;
                case "Cut"://指定高宽裁减（不变形）                
                    if ((double)originalImage.Width / (double)originalImage.Height > (double)towidth / (double)toheight)
                    {
                        oh = originalImage.Height;
                        ow = originalImage.Height * towidth / toheight;
                        y = 0;
                        x = (originalImage.Width - ow) / 2;
                    }
                    else
                    {
                        ow = originalImage.Width;
                        oh = originalImage.Width * height / towidth;
                        x = 0;
                        y = (originalImage.Height - oh) / 2;
                    }
                    break;
                default:
                    break;
            }

            //新建一个bmp图片
            Image bitmap = new System.Drawing.Bitmap(towidth, toheight);

            //新建一个画板
            Graphics g = System.Drawing.Graphics.FromImage(bitmap);

            //设置高质量插值法
            g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.High;

            //设置高质量,低速度呈现平滑程度
            g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;

            //清空画布并以透明背景色填充
            g.Clear(Color.Transparent);

            //在指定位置并且按指定大小绘制原图片的指定部分
            g.DrawImage(originalImage, new Rectangle(0, 0, towidth, toheight),
                new Rectangle(x, y, ow, oh),
                GraphicsUnit.Pixel);

            try
            {
                //以jpg格式保存缩略图
                bitmap.Save(thumbnailPath, System.Drawing.Imaging.ImageFormat.Jpeg);
            }
            catch (System.Exception e)
            {
                throw e;
            }
            finally
            {
                originalImage.Dispose();
                bitmap.Dispose();
                g.Dispose();
            }
        }
    }
}
